[PATCH] D137058: [Driver] [Modules] Support -fsave-std-c++-module-file (1/2)

[Chuanqi Xu via Phabricator via cfe-commits]

ChuanqiXu created this revision.
ChuanqiXu added reviewers: dblaikie, ben.boeckel, iains, tschuett.
ChuanqiXu added a project: clang-modules.
Herald added a project: All.
ChuanqiXu requested review of this revision.
Herald added subscribers: cfe-commits, MaskRay.
Herald added a project: clang.

Patches to support the `one-phase` compilation model for modules. This is the successor of D134267 <https://reviews.llvm.org/D134267>.

@dblaikie suggests to do the following 3 steps to make the `one-phase` compilation model.
(1) Support `.cppm -> .pcm + .o` in one phase. (This patch)
(2) Support specify the path of `.pcm` file in the one phase compilation.
(3) Support the module cache.

Then @ben.boeckel clarifies that the module cache is not necessary. So I won't pursue it too. This patch adds an option `-fsave-std-c++-module-file` to save the module file if we compile the module unit to object files directly. Why a new option? Because I think it may pollutes the space if we make the behavior default. And I feel good to add an option for this behavior.

The behavior:
(1) If `-o` is specified , the module file is in the same path within the same directory as the output the `-o`  specified and with a new suffix `.pcm`.
(2) If `-o` is not specified, the module file is in the same path within the same directory as the input file and with the new suffix `.pcm`.

For example,

  Hello.cppm Use.cpp

A trivial one and the contents are ignored. When we run:

  clang++ -std=c++20 -fsave-std-c++-module-file Hello.cppm -c

The directory would look like:

  Hello.cppm  Hello.o  Hello.pcm Use.cpp

And if we run:

  clang++ -std=c++20 -fsave-std-c++-module-file Hello.cppm -c -o output/Hello.o

Then the `output` directory may look like:

  Hello.o  Hello.pcm

Can we compile the `Hello World` example in one command line? Yes! we can do the following one:

  clang++ -std=c++20 Hello.cppm  Use.cpp -fsave-std-c++-module-file -fprebuilt-module-path=.



---

I'll add the ReleaseNotes and documentation after the series got accepted.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D137058

Files:
  clang/include/clang/Driver/Options.td
  clang/lib/Driver/Driver.cpp
  clang/test/Driver/save-std-c++-module-file.cpp


Index: clang/test/Driver/save-std-c++-module-file.cpp
===================================================================
--- /dev/null
+++ clang/test/Driver/save-std-c++-module-file.cpp
@@ -0,0 +1,17 @@
+// RUN: rm -rf %t
+// RUN: mkdir %t
+// RUN: split-file %s %t
+//
+// RUN: %clang -std=c++20 %t/Hello.cppm -fsave-std-c++-module-file -c
+// RUN: ls %t | FileCheck %t/Hello.cppm --check-prefix=CHECK-DEFAULT
+//
+// RUN: mkdir %t/tmp
+// RUN: %clang -std=c++20 %t/Hello.cppm -fsave-std-c++-module-file -c -o %t/tmp/H.o
+// RUN: ls %t/tmp | FileCheck %t/Hello.cppm --check-prefix=CHECK-O
+
+
+//--- Hello.cppm
+export module Hello;
+
+// CHECK-DEFAULT: Hello.pcm
+// CHECK-O: H.pcm
Index: clang/lib/Driver/Driver.cpp
===================================================================
--- clang/lib/Driver/Driver.cpp
+++ clang/lib/Driver/Driver.cpp
@@ -5532,6 +5532,28 @@
     return "-";
   }
 
+  // If `-fsave-std-c++-module-file` is specfied, then:
+  // - If `-o` is specified, the module file is writing to the same path
+  //   with the output file in module file's suffix. 
+  // - If `-o` is not specified, the module file is writing to the same path
+  //   with the input file in module file's suffix.
+  //
+  // FIXME: Do we need to handle the case that the calculated output is
+  // conflicting with the specified output file or the input file?
+  if (!AtTopLevel && isa<PrecompileJobAction>(JA) &&
+      JA.getType() == types::TY_ModuleFile &&
+      C.getArgs().hasArg(options::OPT_fsave_std_cxx_module_file)) {
+    SmallString<128> TempPath;
+    if (Arg *FinalOutput = C.getArgs().getLastArg(options::OPT_o))
+      TempPath = FinalOutput->getValue();
+    else
+      TempPath = BaseInput;
+
+    const char *Extension = types::getTypeTempSuffix(JA.getType());
+    llvm::sys::path::replace_extension(TempPath, Extension);
+    return C.addResultFile(C.getArgs().MakeArgString(TempPath.c_str()), &JA);
+  }
+
   if (IsDXCMode() && !C.getArgs().hasArg(options::OPT_o))
     return "-";
 
Index: clang/include/clang/Driver/Options.td
===================================================================
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -2276,6 +2276,9 @@
   PosFlag<SetTrue, [], "Look up implicit modules in the prebuilt module path">,
   NegFlag<SetFalse>, BothFlags<[NoXarchOption, CC1Option]>>;
 
+def fsave_std_cxx_module_file : Flag<["-"], "fsave-std-c++-module-file">, Flags<[NoXarchOption, CC1Option]>,
+  HelpText<"Save intermediate module file results when compiling a standard C++ module unit.">;
+
 def fmodules_prune_interval : Joined<["-"], "fmodules-prune-interval=">, Group<i_Group>,
   Flags<[CC1Option]>, MetaVarName<"<seconds>">,
   HelpText<"Specify the interval (in seconds) between attempts to prune the module cache">,


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D137058.471912.patch
Type: text/x-patch
Size: 2817 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20221031/c1697ea6/attachment.bin>